Metallurgical furnace



Oct. 9, 1928.

H. BUTT METALLURGICAL FURNAGE Filed March 25, 1925 2 Sheets-Sheet INVENTOR l l l f l 1 l f 1 jnouuunnooaneauuuone L WITNESSES Oct. 9, 1928. 1,687,470

H. BUTT METALLURGIGAL FURNACE Filed March'z, 1925 2 sheets-sheet 2 INVENTOR m )10u/ard' Buit JM @M7 y@ ATTO EY Aao Patented Oct. Q, 1928.- l

UNITED STATES PATENT OFFICE. e

HOWARD BTT, OF- WORCESTER, ASSACHUSETTS, ASSIGNOR TO RILEY STOKEB COR- `ILOZBIA-TION, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS. I

MTALLURGICAL FURN ACE.

.inplannen area Maren as, 1925. semi No. 18,157.

This invention relates to metallurgical furnaces and more particularly to the construction of a metallurgical furnace which has a heating chamber and a fuel combustion furnace associated therewith.

In the metallurgical industry, a melting furnace, such as is used in an iron foundry, has ordinarily been heated by a combustion furnace which is .hand-fired and is accordingly intermittent in its operation. vA coal burninfr furnace of simple design having a manualy operated dumping grate is usually built in front of the bridge wall of the melting hearth. The fueI is fed throu h a door in the furnace wall onto a ledge Wit in-the furnace where it is permitted to remain fora short time, after which it is pushed onto the burning .fuel bed and another charge is placed on the ledge. This is done to produce gas and a consequent long flame which will reach into the melting zone. During ,the comparatively long time that the door is open for replenishing the fuel, a considerable amount of oxygen is admitted into the furnace, and consequently the bath of melting iron is subjected to the alternating infiuences of reducing and oxidizing flames. This results in a considerable variation in the oxygen content of the iron and of course has a marked effect on the quality and physical characteristics ofthe metal produced. p

Numerous attempts have been made to employ an automatic fuel feeder with a metallurgical furnace but they have not been heretofore successful. The advantages inherent in stoking such a furnace automatically and continuously are obvious. One important the produc-twill be kept more nearly uniform and the operation of the furnace will be materiall simplified and less manual labor will be required to control the furnace.

It is accordingly one object of my invention to secure theseI advantages and to provide a metallurgical furnace into which the fuel may be fed automatically and which will be highly ellicient in its operation and produce a substantially uniform product.

A further object is to provide a metallurgical furnace with a self heated gas producer which is so constructed and arranged that it Will produce a large amount of combustible gas at a uniform rate 'and will maintain a reducing flame for the proper heat treatment of material in the heating chamber.

' With these and other objects in view as will be apparent to one skilled in the art, my invention resides in the combination of parts set forth in the s ecifcation and covered by the claims appen ed hereto.

' In accordance with my experimentations, I have discovered'that a metallurgical furnace havin a heating chamber separated from a com ustion furnace by a bridge Wall should involve certain well-defined principles of construction. The combustion furnace should be so constructed that the fuel will not -be burned completely therein, but ases will be distilled from the coal to a arge extent.` These should be passed over.

the bridfrewall to the heating chamber and burned there as a long ame c osely ad'acent tothe material to be treated. In or er to produce a reducing gas in a self contained automatically operated furnace, I find that I preferably introduce the coal into the combustion furnace at a point near the passage through which the combustible gases enter the heating zone. The fuel is fed progressively into an underfeed retort in the furnace, to form a deep bed from which the volatile matter may be distilled, and is gradually moved laterally on to a support towards an ash discharge. Air is introduced to the interior of the fuel bed on the support to cause combustion and furnish heat for distilling Volatile products from the fuel in the retort. A further limited amount of air is supplied to the retort to aid inthe production of combustible gas. The furnace walls areso ,constructed and arranged that heat from the burning fuel is reflectedonto the green fuel in the retort, and insufficient space is provided over the fuel for the gases to burn there so. that they must pass over the bridge wall into the heating chamber for combustion. Furducer gases by the time they reach the heating chamber so that the llame is vof substantially uniform character.

Une simple embodiment of this invention applicable for melting metals comprises a deep fuel retort located close to and parallel with the front bridge wall of the melting hearth. vThe fuel is fed automatically through a side wallof the furnace into this retort and is caused to move gradually away from the bridge wall over an extension fuel support arranged laterally of the retort which terminates with an ash discharge. I prefer a construction in which the extension supbustion furnace.

cordance with any approved plan as is well understood by those skilled in the metallurgical art, and detailed description thereof is not necessary for a complete understanding of my invention.

The fuel combustion and gas producing furnace is located in advance of the opening over the bridge wall 14, and in order that there maybe no lossof heat I prefer that this bridge wall form the rear wall ofthe com- For the purpose of producing combustible gas rapidly and in large quantity, I preferably rovide a furnace construction which has-a eep retort 18 in front port comprises branch retort-s opening into \.of the bridge wall 14 and a suitable number of branch retorts .19 opening into the main and extending laterally of the main retort and towards the front of the furnace, the far ends of the branch retorts connecting with the ash discharge. Air is fed under suitable pressure through tuyres so located that the major portion of the combustion takes l place preferably at points remote from the -main retort and the heat is transmitted thereto to distill gas from the fuel.' For this purpose I may employ tuyres between the branch retorts or otherwise suitably located. I prefer also to have the furnace roof slope forwardly so as to reflect heat onto` the entering' fuel, and the roof is located comparatively close to the fuel bed so as to limit materially the combustion space over the fuel.

Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts:

Fig. 1 is a vertical elevation of my metallurgical furnace taken on the line 1-1 of Fig". 2; y t

ig. 2 is a .horizontal section on the line 2*-2 of Fig. 1 ;l l

Fig. 3 is a vertical section on the line 3--3 of Fig. 1;

Fig. 4. is an enlarged detail view showing a vertical side elevation partly broken away of the gas producing combustionV furnace;

Fig. 5 is a perpesctive view partly broken' away looking lengthwise of the furnace; and

Fig. 6 is an enlarged fragmentary vertical section of a tuyre block and the adjacent retort sides.

Referring particularly to the drawings, I have there shown a melting furnace comprising a hearth 10, side walls l1, and a roof 12 thereover which is ordinarily formed of bungs 13 or separate arch structures capable of being removed for introduction of material into the melting zone. A bridge wall 14 is located at the front end of the hearth and a second wall 15 near the rear end, space being provided over the two end walls and beneath the roof to form a suitable passage for the gases and products of combustion. The passage over the rear wall connects with a flue 16 opening into the stack. It will be understood that the construction of the hearth and associated furnace parts may be in, ac-

retort.

The main retort comprises a rear wall plate 20 surmounted by tuyre plates 21 extending from one side wall 1l of the furnace to the other parallel with the bridge wall. The front Wall of this retort is made up by the spaced rear walls 22 of the tuyres between the branch retorts which are so shaped and located that the branch retorts merge into the main retort. Thev effective bottom of the main retort is a sliding plate 23 located over the bottom plate 24 supported on suitably arranged I-beams 25 carried by the bridge wall 14 and a partition 28. The branch retorts are made of U-shaped castings having bottoms 26 which are continuations of the bottom plate 24. The branch retort bottoms 26 are horizontal at their rear ends but slope upwardly towards the front of the furnace and join with horizontal plates 27 extending across the furnace. The .front ends of the branch retorts are so shaped that they may be suitably supported by a transverse I- beam 29 which is in turn supported by the longitudinal I-beams 25.

As will be apparent by inspection of Fig. 6, the side walls 30 of the adjacent branch retorts are spaced apart and form hollow air spaces beneath. The tops of these walls are surmounted by hollow tuyre blocks 3l having air openings 32 therethrough cornmunicating with the wind box 33 beneath the retorts which is separated from the ash pit 35 by the partition 28. The plates 27 may have tuyre openings 34 therethrough and all of the various tuyres will be in communication with the wind boX. Air under pressure is admitted to the wind box through an inlet pipe 36 connected with a blower, and the pressure of the air may be suitably regulated by dampers and other devices.

Ash dump plates 37 are hinged to a ribbed support carried on an upright plate 38 on the top of the wall 28, and they are so constructed and arranged that they will normally remain in a horizontal position and support the fuel bed thereove-r, but may be swung downwardly by suitable mechanism to dump the material into the ash pit. These plates have tuyere openings 39 therethrough, and air may be admitted from the wind box thereto through a slide valve ,40 in the artition pla/te38, which may be suitably adgusted by a rod connected thereto and passing to a point outside-the furnace walls.

blocks 45, which preferably have verticalv front walls and rearwardl sloping tops so arranged that they ynot on y cooperate with A `the ram to feed the fuel forward through the main retort, but they tend to lift the fuel bed as they move backwards, thus keeping the coal bed loose and preventing the formation of large coke masses,

.As a suitable means laterally into the'branch retorts, I preferably provide pusher blocks whichv are arranged one in each branch retort and are so connected to operating mechanism that they will reciprocate in alternate directions at the same time, thereby tending not only to move the fuel laterally into these' branches but to slice the fuel bed along lines between adjacent retorts. These branch pusher blocks and 51, as shown particularly in Fig. 4, mayv have flat bottoms .adapted to .slide on the horizontal portion of the floor 26 and tops so shaped that the will slide beneath the plate 23. A wedge-s aped nose 52 is preferably provided so that the coal as it is moved forward will be given a lifting motion. These lateral pusher blocks may be reciprocated by any suitable mechanism such as cranks 53 and 54 operated by a steam engine connection. The cranks are connected by the links 55 and 56 with lugs rejecting from the bottoms of the pusher locks through slots in Vrn ' amount of the gas to the oor 26. The pusher blocks 50 and 51 are also providedwlth rollers 57 .whichscontact with the underside of the bottom plate 24 and thereby keep the pusher blocks from being lifted from contact with the horizontal portion ofthe floor 26 by an accumulation of coal therebetween.

It will be noted by inspection of Fig. 1 that tion furnace has been made to slopeV downwardly toward the front of the furnace so as to rovide a very small space over the fuel bedP forthe volatile ases. Their rate of travel is so regulated `t at although they are mixed with air for complete combustion, there will be no op ortunity for a large mrn over the fuel bed roat 42 into the lower portion of for 'moving the coal` but it must pass over the bridge 'wall and burn over the melting hearth. Thatv is, the furnace is essentially a gas producer, and only so much fuel should beburned therein as is necessary for an efficientv product-ion of combustible gas.

The sloping wall of this roof has another function. The green fuel is fed into the main retort to form such a deep bed that' it cannot readily burn except adjacent the. top layer near the tuyre openings, hence it is necessary that heat be introduced into this large mass of coal so as to distill the volatile mat- \ter therefrom. v The upwardl sloping retort bottoms 26 and the downwar ly sloping tops of the tuyre blocks 31 are so Aarranged that the fuel bed gradually decreases in thickness from the rear of the furnace towards the dump plates. The tuyre openings, as may be seen infFig. 4, gradually approach the bottom of the fuel bed towards the front ofv the retorts, hence the combustion of the fuel becomes more pronounced towards the dump plate. In order to use efficiently the heat thus generated, I slope the roof so that it will reflect this heat downl onto thedeeper portions of the lfuel bed, thereby serving to raise the temperaturel therein to a material extent.

It will be observed that the tuyre plates 21 are so constructed that air is admitted into the main retortonly through openings 60 at thelower ends of the plates, so that there is little opportunity for the fuel in this retort to burn. I may in some cases omit all or a-larger part of these tuyre openings. Similarly, the upper portions of the tuyre blocks 61 which form the tops of the outer walls of the two end lateral retorts are left blank and air is admitted to .a limited extent through the openingstherein located on a level with the tuyre openings 32. These blocks and the blocks 21 are arranged to project above the tops of the tuyre blocks 31 sc as to hold the fire away from' the side walls of the furnace; but, as illustrated, the'air inlet openings are preferabl few in number and small in size so as to minimize combustion butvinsure proper cooling of the plates. In other words, I provide such a construction` andI so operate the furnace that the coal is burned only sufficiently to provide the necessary heat for producing a combustible gas. It will be obvious that various changes may be made in the tuyere and retort structures in order to admit air into such portions of the furnace as seems most desirable toobtain the maximum efciency, provided the furnace is so operated to make it vsubstantially a gas producer. l i

In operating the furnace, coal is fed from the hopper 41 into and along the main retort and then7 into the branch retortsby the pusher blocks. The coal is fed at such a rate that it piles up into a high bed .of coal over the tops of the tuyeres. Suflicient air under suitable pressure is admitted to form a hot flame at the 

